Hot-air engine.



No. 650,576. Patented nay 29, |900.

J. WICKSTRUM.

HOT AIR ENGINE.

(Application led Apr. 26, 1898.)

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, Patented May 29, |900. J. WICKSTROM.

HUT AIB ENGINE. (Appncmon med Apr 26,1598

JOM #ic/Ks'ron NITED STATES- `'PAIENI OFFICE.

JOI-IN wICKsrRoM, OE CI-IICAcO, ILLINOIS, AssIGNoa, BY DIRECT AND MEsNE ASSIGNMENTS, To .IOIIN T. EANNING, OE sAME PLACE.

HOT-AIR ENGlNE.

SPECIFICATION forming part of Letters Patent No. 650,576, dated May 29, 1900. Application filed April 26, 1898.` Serial No. 678,838. (No model.)

To all 11171/0771/ t may concern,.-

Be it known that I, JOHN WICKSTROM, of Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Hot-Air Engines; and I d0 hereby declare that the following is a'full, clear, and exact description thereof, reference being had to the accompanying drawings, and to the letters of reference marked thereon, which form a part of this specification.

This invention relates to improvements in hot-air engines of that class which are provided with apower-piston and with a transferpiston which is actuated from said power-piston to transfer the air from the hot-air chamber to the cooling-cylinder, and vice Versa.

The invention relates more particularly to an improved connection between the powerpiston and crank-shaft and between the latter and the transfer-piston and to an improved construction of the power-piston by which the air is more effectively cooled While it is being transferred from the hot-air chamber to the cooling cylinder and also by which air is more eectively used by reducing the cool clearance-space in the engine during the expansion of the air therein.

The invention relates, further, to other improvements in engines of this character, as will hereinaftermore fully appear.

In the drawings, Figure I is a View, partly in side elevation and partly in vertical section, of an engine constructed in accordance with my invention. Fig. 2 is a View, partly in front elevation and partly in section, taken on line 2 2 of Fig. l. Fig. 3 is a perspective detail of one of the connecting parts between the piston and crank-shaft. Fig. 4 is a diagram showing the relative positions of the different parts of the engine at the various,

positions-of the crank-arm in the revolution thereof.

In said drawings, A designates a base eastin g or support which sustains the various operativeparts of the engine, said casting being sustained upon legs A.

B designates a power-cylinder, which serves also as a cooling-cylinder; B', a piston therein; C, a hot-air chamber; D, a burner for heating said chamber, and E a transfer-piston which reciprooates in said cylinder and hot-air chamber. D' designates as a whole avaporizing device which supplies fuel to said burner. The hot-air chamber is connected with the power-cylinder through an intermediate cylinder C', which is hereinafter considered as a part of the hot-air chamber, and such chamber and intermediate cylinder and power-cylinder are connected together in axial alinement by bolts passing through outwardly-extending radial Hanges thereon, as shown. Said hot-air chamber and power-cylinder are sustained in vertical position, as herein shown, upon the bed A in any suitable manner, the bed being provided with a circular opening through which the lower end of the hot-air chamber depends. Said lower end of the hot-airchamber is surrounded with a casing which directs the heat to said chamber and prevents its radiation therefrom. Said casing consists in the present instance of an inner lining C2, of asbestos or other suitable non-conducting material, and an outer coverin g C3, of sheet metal, which is attached ,to the bed or base casting A in any suitable manner. Said casing is provided in its bottom with an opening through which the burner D extends and will be provided with an exitpipe (not shown) for the escape of the products of combustion.

F designates a crank-shaft, which is connected with and driven by the piston B. The connectin g means Consists of an intermediate sector-shaped rocking lever G, which is pivoted at its vertex to a stationary standard A2, connected rigidly in any suitable manner to the bed-plate A, a pitman G', which connects said rocking lever to the crank-arm F' of the crank-shaft, and a connecting-rod G2,Which is pivoted at one end to an extension G3, attached to or formed integral with said lever and which is pivoted at its other end to the piston.

The transfer-piston E is operated from the crank-shaft by means which give it a variable motion with respect to the power-piston.

The driving means between thetransfer-piston and the crank-shaft consists of a rocking lever H, which is pivoted to the upper end of the standard A2 to swing in a vertical plane between said rocking levers G and which is connected to an arm G4, formed rigidv with the pitman G' and at an angle thereto,

IOO

as herein shown, by means of a connectinglink H'. Said rocking lever H is connected at its outer end by means of a link H2 with a connecting-rod H2, which latter is attached at its opposite end to the transfer-piston inside of the power-piston, said connecting-rod passing through a stu fing-box b in said powerpiston.

The power-'piston ts closely within th cylinder B, (which is in this instance open at its outer end,) so as to prevent the escape of air past the same, and is provided on its inner side with a rigid sleeve B2, which extends into the intermediate cylinder C'. Said sleeve is of less external diameter than the piston proper, thereby forming between the same and the inner wall of the power-cylinder when the power-piston is moved outwardly, so that a portion of the sleeve occupies said cylinder, an Vannular space, as indicated at Z9. The lower end of the power-cylinder is reduced in diameter, as indicated at b2, so that the sleeve B2 fits closely therein at this point to form an air-tight joint. Conveniently the piston will be made of two parts-an upper part B2, to which the connecting-rods G2 are attached, and a lower part B4, with which the sleeve B2 is integrally cast. Said lower part of the piston isrv of less diameter than the upper part thereof, and a packing b3 is interposed between the same and the cylinder and is held in place between the upper and lower plates forming said piston.

' The transfer-piston consists of a hollow cylindric shell, which is desir-ably formed from sheet metal by a drawing operation and is made of such diameter as to fit closely within the inwardly extending sleeve B2 of the power-piston. Said transfer-piston is made air-tight, the inner end thereof being formed integral with the body of said shell and the outer end being formed by means of a castmetal disk E', which is fitted closely within theouter end of the shell and secured `permanently therein in any suitable manner. The met-al of the piston is braced Vfrom inward distortion from external pressure of the air by means of internal transverse rings E2, secured rigidly thereto. `Said transferpiston is made of considerable 4length in order to separate the hot-air chamber from the power or coolingcylinder a suilcient distance to prevent the conduction of heat from said hotair chamber to said cylinder. In order to further insulate the power-cylinder from the hot-air cylinder, disks E2, of asbestos or like non-conducting material, are laid upon the strengthening-rings E2. Communication is established between said hot-airchamber and power-cylinder and inside of the power-piston by means of a passage C4 in the wall of the intermediate cylinder C', which opens at one end into an annular recess b5 in the inner Wall of the power-cylinder between the point therein occupied by the piston when at the limitof its inner stroke and the reduced portion b2 and .in communication with the ,C4 contains a body of air which acts to transmit the pressure from the hot-air chamber to the power-cylinder, and said passage acts also to convey air from the hot-air chamber to the power-cylinder, and vice versa, when displaced by the transfer-piston. The transfer-piston is operated at the completion of the outward stroke of the power-piston to displace the heated and expanded air in the hot-air chamber and to force it through the 4regenerative passage 'C4 and through the cooling-space b' in the power-cylinder to the space between the power and transfer pistons and to force said air from said cylinder after it has become cooled and lpreceding the next power-stroke to the hot-air chamber in .order that it may be again heated.

The lower end of the hot-air chamber is provided interiorly with a cylindric casing or lining C5, which fits at its upper end closely into the lowerend of the intermediate cylinder above the annular recess c, into which the passage C4 opens, and is made of s-uch eX- ternal diameter in its part below said recess as to provide between the same and the inner `Wall of the chamber an annular space c', which is termed a heating-space, through which the air passes to the lower end of the hot-air chamber, and which space communicates with the interior of said casing C5 through a port c2 at the lower end of the casing. Said annular heating-space c is provided for the p u rpose of causing the air to be spread out in a thin sheet in contact with the heated inner walls 4of the hot-air chamber in its passage to the lower end of said chamber, so that its temperature will be more rapidly raised than if it were introduced at once into said chamber in a relatively-large body.

As a means for reducing the temperature of the air as it passes from the hot-air chamber 'to the power-cylinder a regenerative device IOS IIO

hereinafter more fully appear, that when the air in the hot-air chamberand force it to the power-cylinder the power-piston will be near the outer limit of its power-stroke, so that the air which is driven from said hot-air chamber in order to enter the port b to the space between said power-piston and transfer-piston will need to pass through the annular cooling-space 7)', which is at this time increased in length over that shown in the drawings, owing to the movement of said piston outwardly, so that the air will be directed in a thin sheet against a relativelylong cold surface of the power-cylinder and will be thereby further cooled. The walls of the powercylinder are provided with a water-space B6, through which cold Water is forced and by means of which said walls are maintained cold. bw b designate, respectively, the inlet and outlet passages to said space. V designates a pump-cylinder; V', a pitman or connecting-rod which is connected at its lower end with a piston (not shown) in said cylinder; V2, a sliding head which slides in vertical guides V3, located on standards V4 on the base-plate A, and which head is connected with the pitman V'; V5, a connecting-rod which is connected at one end with said head and at its other end with a crank V", which is connected with a gear-wheel V7, mounted on a shaft VS, support-ed on said standards V4, and which gear-wheel meshes with a gearpinion V9 on the crank-shaft F. Rotation of said pinion and gear-wheel serves through the crank V to give motion to the head V2 and therethrough to the pump-piston.

l The operation of the engine made as thus described will be best understood by reference to the diagram shown in Fig. 4 and will be explained in connection therewith. In said diagram the circular path of the crankarm is indicated by F and is divided into twelve equal parts and numbered from 1 to 2, inclusive. The paths of the pistons, the levers G and l-I at their points of connection with the connecting-rods D2 and H3, the pitman G at its point of connection with the lever G, and the arm G4 at its point of connection with the link H', by which it is connected with the lever H, are also indicated, and the lines indicating the same are divided into twelve parts to indicate the positions of these various parts in their paths of movement during each one-twelfth revolution of the crankarm. The diagram indicates the positions of the parts of the engine, as shown in Fig. 1 that is to say, with the piston at the beginning of its outward or power stroke under the impulse of the expanding air. In said diagram, P indicates the direct line on which the pistons travel; G, a line which passes through the upper member of the sector-shaped lever G and the projection G3 thereof; H, the center line of the lever H; Gb, the center line of the pitman G; Gc, the center line of the arm G4, and Hc the center line of the link H. A4 indicates the point of pivotal connection of the lever G with the standard A2, and Ab the point of connection of the lever H with said standard. Hb indicates the arc through which the end of the lever H moves; G4, the arc through which the extension G3 of the lever G moves; Ge, the arcl through which the lower member of the sector-shaped lever G at its point ot'attachment with the pitman G moves, and Gf the curved path through which the outer end of the rigid arm G4 of the pitman moves. The line P is divided into twelve parts to indicate the different positions of the power-piston to correspond to the divisions in the circular path of the crank-arm and is divided into twelve other parts to indicate the corresponding positions of the transfer-piston. The positions of said pistons in the return stroke are shown on the right-hand side of the line, and the positions in the outward or power stroke are indicated on the left-hand side of said line. the power-piston are further indicated by the shorter lines having the prefix l? and the transfer-piston by the longer lines and desig- The different positions of nated by the prefix T. The lines indicating the movementsof the levers H and G and the extension G3 of said latter lever, as well as Y the curved line whichvindicates the movement of the outer end of the rigid arm G4 of the pitman G', are similarly divided. From an y inspection of the diagram it will be seen that Y also be seen that from the position shown, in

which the piston is beginning its outward movement uder the influence of the expand- IOO ing air, the transfer-piston and the inner face,

of the power-piston are almost in contact-with each other and that they move towardthe outer end of the cylinder in substantially the same relation, being separated onlya slightlygreater distance atthe limit of the outward stroke of the transfer-piston than at the point, indicated as to the positionsV of the pistons in. the diagram. This result is secured by the relation of the rigid arm G4 to the pitman and to the points of pivot of the leversG and H during that part of they revolutionv of the crank-arm in which the power-piston is accomplishing its effective work, said arm at this time occupying such position with relation to the other parts thatV the movement given by the power-piston to the, crank-shaft will be transmitted uniformly from said shaft to the lever H, so that said le-` ver will move parallel with the lever G. Vhen the crank-arm has passed through the arc of its revolution mentioned, the arm G4 ofthev pitman will be oscillated laterally, owing to4 its angular relation with the pitman, whichv will act through the link H' to move the lep piston and begins its return stroke b efore the power-piston has completedits power-stroke, v

so that the distance between said pistons at the beginning of the return stroke of the power-piston is increased, as indicated by the 'distance between P and T' on the line P. In

the further revolution-of the crank-arm the,

speed of the transfer-piston with relation to the power-piston is greatly accelerated, as indicated bythe lines T" T2 T3, &c., thereby providing a space between said power and transfer pistons to receive the air which is displaced by the latter piston in the hot-air chamber and forced through the passage C*v The air which is drive-n from E to said space. y said hot-air chamber and which is highly heated gives off a portion of its heat as it passes through the regenerative device I, and when it comes in contact with the cool surface of the cylinder as it passesl through the annular cooling-space t between said cylinder and the sleeve of the piston and before it entersl the space between the transfer and the power pistons is further reduced to about the normalitemperature of the surrounding atmosphere. It will be noted by an inspection of the diagram that the inward displacing stroke of` the transfer-piston `is accomplished in the irst ive-twelfths of the revolution of the crank-arm, while the return stroke of the power-piston is not completed until the crankarm has passed through seven-twelfths of 'its revolution. During the time the crank-arm is passing through the space-from the fifth to the eighth twelfth of its revolution the transfer and power pistons are moving toward each other and the air which is between the sanne is at this time forced through the passage C4 to the hot-air chamber. The direction of the power-piston is reversed just before coming in contact with the transfer-piston, and the connections between the crank-shaft and the transfer-piston are such that the latter will assume the relation tothe power-piston shown in Fig. 1 at the instant the crank-arm has passed its lower center, so that at this time all of the air will be forced from the cool spacev between said pistons and driven to the hotair chamber. The air on passing through the regenerative device will absorb the heat retained thereby from the air during its last passage therethrough and will be spread in a thin sheet in contact with the heating-surface of the annular heating-space c',so that it reaches said hot-air chamber in a heated condition.

The air while being forced into the hot-air chamber and just before the crank-arm has passed its lower center will be placed under compression by the addition of heat thereto,

so that when the crank passes its lower center the pressure of the air within the hot-air chamber will act to force the piston outwardly. The further heating of the air within the hot-air chamber will cause it to further expand and drive the power-piston outwardly y in the manner before stated.

The means herein shown for driving the transfer-piston from the crank-shaft possesses l great simplicity over drivingA connections heretofore employed for this purpose, as by the means shown said transfer-piston is more directly connected with the crankshaft,which insures prompt and efficient action thereof. Furthermore, the connecting part G4 between the pi'tman and lever H being rigid with the pitman and bearing a definite relation to said pitman enables the rockin glevers H and G, which are directly connected with the transfer and power pistons, 'to be maintained in parallel relation during that part of the revolution of the crank-arm in which the eective part 'of the stroke is being made, so that said pistons move outwardly together until the power-piston is near the end of its powerstroke,when the lateral oscillation of said rigid part G4 will act to move `the lever H and piston E quickly downward to edect the displacement of the heated air Vin the hot-air chamber. `The arrangement described enables the'movement of the transfer-piston to be controlled with great precision, so that said transfer-piston maybe moved outwardly, together with the power-piston in the powerstroke of vthe latter, and be moved inwardly to displace the hot air in the hot-air chamber and returned in contact with the power-piston when the latter begins its next powerstroke. The construction described wherein the power-piston is'provided with an inwardlyprojecting sleeve in which kthe outer end .of the transfer-piston fits and slides is of great importance, for the'reason that it enables the annular cooling-space b to be regulated independently of the movement of the transferpiston, so that a large portion of the air from the hot-air chamber will be forced through the annular cooling-space b' before its length has been materially reduced, thereby effectually coolingthe air. Obviously if nosleeve were provided having inlet-ports, as h6, adjacent to the power-piston the length of the coolingsurface with whichthe air is brought into'contact as it passesbetween the power and transfer pistons would decrease in the same .proportion as the transfer piston isvmoved inwardly, it being evident that the air would not pass beyond the outer end of the transfer-piston. Furthermore, said construction permits the cool clearance of the engine to be reduced to a minimum at the beginning of the power-stroke of the'piston, so that the power of the expanding air can be most advantageously employed.

It will be understood that while the cylinder B has been termed a power-cylinder it also performs the function of a cooling-cylinder and that this double function will always be un derstood in connection with the cylinder.v

' as made the subject of specific claims.

I claim as my inventiony 1. In a hot-air engine, the combination of a IOO IIO

ISO

power-cylinder, a hot-air chamber', a piston in said power-cylinder, provided with an inwardly-extending sleeve, a transfer-piston between the power-cylinder and hot-air chamber and sliding in said sleeve, and means connected with the power-piston for driving said transfer-piston.

2. In a hot-air engine, the combination of a power-cylinder, a hot-air chamber, a piston in said power-cylinder provided with an inwardly-extending sleeve, ports in said sleeves adjacent to the piston, apassage leading from said hot-air chamber and connected with said ports, a transfer-piston between the powercylinder and hot-air chamber and sliding in said sleeve, and means connected with the power-piston for driving said transfer-piston.

3. In a hot-air engine, the combination of a power-cylinder, allot-air chamber, a piston in said power-cylinder provided with an inwardly-extending sleeve which is of less external diameter than said piston and which fits closely within the lower end of said cylinder, ports in said sleeve adjacent to the said piston, a passage leading from the hotair chamber and connected with said ports, a

transfer-piston between said power-cylinder and hot-air chamber and slidingin said sleeve, and means connected with the power-piston for driving said transfer-piston.

4. In a hot-air engine, the combination of a power-cylinder, a hot-air cham ber, apiston in said power-cylinder provided with an inwardly-extending sleeve which is of less e'X- ternal diameter than said piston and which fits closely within the lower end of said cylinder, ports in said sleeve adjacent to said piston, a transfer-piston between said powercylinder and hot-air chamber and sliding in said sleeve, a passage external to said sleeve connecting said hot-air chamber and the power-cylinder outside of said sleeve, and means connected with the power-piston for driving said transfer-piston.

5. In a hot-air engine, the combination of a power-cylinder, a hot-air chamber, a piston in said power-cylinder provided with an inwardly-extending sleeve, ports in said sleeve adjacent to said piston, a transfer-piston between said cylinder and hot-air chamber which closely fits in said sleeve of the piston,

a passage external to said sleeve connectingl the said cylinder and hot-air chamber, a regenerative device in said passage and means connected with the power-piston for driving the transfer-piston.

6. In a hot-air engine, the combination with a power-piston provided with an inwardlyextending sleeve, of a transfer-piston fitting and sliding in said sleeve as and for the purpose set forth.

7. Inahot-air engine, the combination with a power-cylinder and a hot-air chamber, of a piston provided with an inwardly-extending sleeve which is of less external diameter than the internal diameter of the power-cylinder, a transfer-piston between the power-cylinder and hot-air chamber, and means for driving said power and transfer pistons.

8. In ahot-air engine, the combination with a power-cylinder and a hot-air chamber, ofa piston in said cylinder provided with an inwardly-extending sleeve which is of less eX- ternal diameter than the internal diameter of the power-cylinder, a transfer-piston fitting and sliding in said sleeve, a passage connecting said hot-air chamber and the spacebetween the piston-sleeve and the wall of the power-cylinder, said sleeve being provided with a port connecting said space with the space between the power-piston and transferpiston, and means for driving said power and transfer pistons.

In testimony that I claim'the foregoing as my invention I affix my signature, in presence of two witnesses, this 22d day of April, A. D. 1898.

J OI-IN WICKSTROM.

Witnesses:

R. C. VIVIAN, W. A. WHITEHEAD. 

